Next-generation communication system standards use fast adaptive modulation and coding (AMC) combined with multi-user diversity scheduling to provide system capacity improvements for packet data applications. Such systems typically use some form of channel quality feedback that briefs the scheduler with regards to the channel conditions of each mobile. The scheduler uses the feedback to identify which users are in a constructive fade and then to select the appropriate modulation and coding rate based on the reported channel conditions. The feedback is designed to track fading for low mobility (e.g. 3-30 kmph). In a communication system employing the 1xEV-DO system protocol, the feedback rate is 2.4 kbps; a 4-bit channel quality report is sent back every 1.67 ms.
Such communication systems typically utilize a dedicated control channel that is established for the duration of a packet call, and the channel quality feedback is transmitted as part of the dedicated control channel. The dedicated control channel is typically activated when a user requests a web page and de-activated after a period of inactivity by a pre-defined inactivity timer. Current implementations set the inactivity timers as high as 60 seconds, but in the future it may be set as low as 2-to-5 seconds. Even with the lower numbers, ten to one hundred users may be simultaneously maintaining a dedicated control channel depending on the packet data application being used. Because of this, the aggregate rate of all the feedback channels can be as high as 240 kbps. Furthermore, since significant gaps between packets exist (e.g. 200 ms) due to the packet inter-arrival process within a packet call, most of the mobiles do not have a single packet queued while they are providing this channel quality feedback. Thus, the majority of the feedback is unnecessary and wastes uplink resources.
The problem of wasted uplink resources will be exacerbated in future systems, which may require additional feedback in order to communicate the status of frequency selective channels and multiple spatial paths. Therefore, a need exists for a method and apparatus for providing channel quality feedback within a communication system that does not provide unnecessary feedback, wasting uplink resources.